As part of the study being made in the Sound Laboratory of methods for standardizing hearing diagnostic equipment, measurements have been made comparing the sound pressures developed by earphones in several couplers, used at various laboratories in the calibration of earphones, with the sound pressures developed at the entrance to the ear canal when the earphones are placed over the ear itself. The couplers used in the comparison are the NBS Coupler No. 9A, the “Type I” coupler of the American Standards Association Standard for Coupler Calibration of Earphones, and a British coupler developed at the National Physical Laboratory. Necessarily, only a small number of human subjects could be employed. However, these data are being used primarily for orientation with respect to the design of a new coupler which will present to the earphone a better replica of the acoustical load afforded by the ear.